Simultaneously connect to same network using wired and wireless interfaces

[_Nine_]

Hi all,

Currently, in order to access network resources, I have to be connected to a network either via the wired (eth0) interface or the wireless (wlan) interface.  I cannot have both interfaces active simultaneously on the same network.  Yet, I'd like to have both active so that I can be plugged in when I want and then seamlessly roam on wireless when I'm unplugged without first disabling the wired interface and enabling the wireless interface.  However, I can't figure out how to make this happen and my searches so far haven't been fruitful.

I have seen other posts regarding this issue, but none adequately address the cause or offer a solution other than saying to disable one of the interfaces.  Disabling an interface should not be necessary.  You definitely can have multiple interfaces active on a system regardless of whether they are bound to the same network or different networks.  You should be able to connect to as many networks as there are interfaces.  Neither Windows nor other distros such as Fedora and Debian have any problem allowing this capability.  Bridging or any kind of network sharing should not be required unless you're trying to configure routing for some sort of internal network on the system.

Some people have suggested that it's an issue with multiple default gateways.  This makes sense if each interface is bound to separate networks, but in my case, each interface is a DHCP client on the same network and pulls an IP address and the default gateway address from the same router.  The default gateway address is same for each interface.  I shouldn't have to configure one interface with a static IP just to force a blank default gateway address since it's the same gateway setting for each interface. 

Does anyone have any idea about why this behavior exists on PCLinuxOS and not on other OSes including Windows and other Linux distros?  Any idea how to fix it?

Thanks!

_Nine_

[rubentje1991]

I don't know if that's what you mean, but in the (recent) past, when I was connected to a wireless network, and plugged in my network cable, the wireless connection stayed connected.... (and I got also a connection via the network cable)
Don't know which one the pc used (sometimes I disconnected the wireless manually) - but it worked apparently 

[_Nine_]

Yep, that's exactly what I mean.    And I'm guessing you didn't do anything special to make that work?  I don't know why, but everything is fine if I'm connected using either wireless or LAN, but the minute I'm connected to both, it's like I can't reach out to anything.  So, in that sense, it feels like a DNS or gateway/routing issue, but nothing about the routing should be different based on the interface--it's the same default gateway/router regardless of how I connect. 

There have been posts about this issue on other forums, but there are either differences in the scenario (such as the person is trying to connect to two separate networks) or they just don't seem to adequately address it.  There actually is a pretty recent post about it on this forum, but for some reason, I don't have permission to view it: http://www.pclinuxos.com/forum/index.php?action=printpage;topic=95408.0

But, I can look at a Google cached version of the post and based on that, it doesn't seem like the issue was resolved...

I don't have this issue when using other distros, but don't know where to look to see if there's any differences in their default network config vs. PCLOS...the GUI doesn't reveal anything unique. 

I just  can't imagine this is how it is for all PCLOS users as it seems like it would be dealbreaker, especially if you're trying to set up a laptop or something for a less technical user...

[Martin Goose]

Yep, that's exactly what I mean.   

I am also seeing the same thing with a new eMachine PC. http://www.ebuyer.com/267867-emachine-er1401-desktop-pt-nbzec-004 (PCLinuxOS KDE fully updated)

I manually deactivate the wireless every time I reboot. If I don't do this I can always access other PCs on the network, but Internet access does not work (no web, no email, no Usenet). I can ping my ADSL modem/router and an external numeric IP but not a domain that needs a DNS lookup.

On one occasion the PC rebooted while I was away. I came back to the log-on prompt. I have a cron job that runs every 5 minutes to access my ADSL modem/router to record my connection status. When I got home my ADSL modem/router would not let me out onto the internet even after deactivating the wireless because it had decided I had a PC on the network with a possible virus (as if!!). Not sure if this means anything though.

Is there a command to deactivate the wireless as Linux boots?

[Just17]

Strange .....  I have - it seems - different experience .....  if the ethernet cable is plugged in then that is used to connect to the network and when unplugged the wireless connects to the same network.

I did nothing at all except set up the wireless NIC with password.

But this seems to be different behaviour from what is described above ....

[rubentje1991]

Maybe it depends on what networkmanager is used...
=> the default NetworkManager, Wicd Network Manager, ...... 

[pindar]

Does anyone have any idea about why this behavior exists on PCLinuxOS and not on other OSes including Windows and other Linux distros?  Any idea how to fix it?

Hiya,

I had exactly the same problem you are experiencing, and I had a long thread here on the forum about it, but any search for it turns up empty. There are still some links pointing to the thread (http://www.pclinuxos.com/forum/index.php/topic,95624.0.html), but the thread itself appears to be deleted, which I find slightly disturbing - there was absolutely nothing in it which warranted deletion. Anyways: in my case, it turned out that it was a kernel misconfiguration in the latest pclos kernel (2.6.38). You could try installing an earlier kernel and see if this solves your problem.

Good luck

pinda

[Archie]

[AS]

 

[Archie]

Somehow, I think I missed something.

[GermanTux]

Nine, without some background intelligence knowing which interface to defer to (and even them there will be some brief downtime), you cannot do this.  Being connected to both means the IP stack has no idea which interface to send packets out to.  This is all part of basic IP routing.  You may (but even then it is doubtful) be able to do it if the networks are on separate subnets, but in a home use scenario I doubt you want to configure two routers. 

[AS]

Nine, without some background intelligence knowing which interface to defer to (and even them there will be some brief downtime), you cannot do this.  Being connected to both means the IP stack has no idea which interface to send packets out to.  This is all part of basic IP routing.  You may (but even then it is doubtful) be able to do it if the networks are on separate subnets, but in a home use scenario I doubt you want to configure two routers. 

+1 

[_Nine_]

Nine, without some background intelligence knowing which interface to defer to (and even them there will be some brief downtime), you cannot do this.  Being connected to both means the IP stack has no idea which interface to send packets out to.  This is all part of basic IP routing.  You may (but even then it is doubtful) be able to do it if the networks are on separate subnets, but in a home use scenario I doubt you want to configure two routers. 

Hi GermanTux,

Yeah, I definitely understand a brief amount of downtime--that completely makes sense, and I experience that with other OSes.  In Windows or on other distros, I can be connected both to the LAN and WLAN at the same time, but I'm guessing that, by default, all traffic is sent out the LAN interface.  If I unplug, i'll notice a very brief connectivity loss before traffic automatically is sent over the WLAN interface.

But I'm not trying to use the two interfaces at once.  Rather, what I'm saying is that in PCLOS, I can't simply even be connected to both at the same time--even if traffic will be sent across only one.  This means that the LAN interface is active and I'm plugged in, I can't just unplug and then have everything automatically switched over to the WLAN interface.  Instead, I have to manually either activate the WLAN interface or connect to a network on the WLAN interface.  I can't have my wireless network connected and "waiting in the wings" so that I can "failover" or seamlessly move between LAN and WLAN connectivity. 

Other OSes have a mechanism for handling this automatic switching, and I'm guessing that's the experience for most PCLOS users on here (or at least I hope!).  I can't imagine that PCLOS laptop users here have to manually invoke their wireless connection when they unplug from the LAN connection...

So maybe it's a kernel issue like pinda suggested?

--Brad

[GermanTux]

Windows will connect to both.  But it does not default to one.  Sometimes you will go out the wired connection, sometimes the wireless.  all the while probably suffering significant packet loss.  There is a command line method inside Windows to prioritize one interface over another. 

Your best bet is to keep the wireless off when plugged in.  Then turn it on when you disconnect.  After about 45 seconds the wireless should be connected, and you are on your way. 

[Dulwithe]

Hi all,

Currently, in order to access network resources, I have to be connected to a network either via the wired (eth0) interface or the wireless (wlan) interface.  I cannot have both interfaces active simultaneously on the same network.  Yet, I'd like to have both active so that I can be plugged in when I want and then seamlessly roam on wireless when I'm unplugged without first disabling the wired interface and enabling the wireless interface.  However, I can't figure out how to make this happen and my searches so far haven't been fruitful.

_Nine_

I have been frustrated many times with the exact same issue.

D.